All human cells require a constant oxygen supply to maintain cellular structure and function. When oxygen delivery decreases below Pasteur's point, cells undergo anaerobic respiration. Clinically, this can lead to critical organ dysfunction (e.g., brain and myocardial injury), which could result in death if not rapidly corrected. Impairments in oxygen supply can occur during airways obstruction, parenchymal lung disease, or impairments in pulmonary blood flow, circulation, blood oxygen content, and oxygen uptake. Brief interruptions in ventilation or pulmonary blood flow can cause profound hypoxemia, leading to organ injury and death in critically ill subjects.
Providing even a small amount of oxygen supply may significantly reduce the death rate or the severity of tissue damage in subjects suffering from hypoxia. One conventional attempt to restore the oxygen level in a patient is supportive therapy of patient's respiratory system (e.g., mechanical ventilation). This approach may be insufficient to fully reverse hypoxemia in patients with lung injury. Emergency efforts such as lung recruitment maneuvers, increased fraction of inspired oxygen or inhalational nitric oxide are other approaches used to deliver oxygen to a patient. However, in some instances these may be inadequate and/or require too long to take effect due to lack of an adequate airway or overwhelming lung injury.